I'm sure you'll be fine -- don't worry. I wish you had an appointment with a Neurologist instead of an internist, just to be safe. I tend to agree that it is probably panic attacks, as they CAN bring on some pretty strange symptoms. I had panic attacks some years ago myself, and had some pretty weird symptoms! But just to be sure, I would have preferred that you see a Neurologist. An internal medicine doctor is not the appropriate doctor to see. Those doctors usually deal with stuff like diabetes, diseases of the organs, etc.
Your doctor should NOT have laughed at you because you suggested a brain tumor or anything else for that matter. You have FEARS and they're legitimate! Just because we're afraid of something doesn't rate being laughed at! That makes me MAD. Your doc SHOULD have referred you to a neurologist, and admitted that she doesn't know what's going on! But she's arrogant and just doesn't like to admit that she doesn't know.
I wish you the very best. PLEASE let us know what happens, OK?? We do care here -- I hope to hear from you when you find out. God bless & take care. Hugs, Lee